CARACAS, Venezuela — Tens of thousands of chanting supporters of Venezuelan President Hugo Chavez rallied outside his presidential palace Thursday in an exuberant alternative inauguration for a leader too ill to return home for the real thing.

Backers wearing T-shirts with the slogan “I am Chavez” waved flags while upbeat music from Chavez’s last presidential campaign blared from speakers, proclaiming: “Chavez, heart of the people!”

The government organized the unusual show of support for the cancer-stricken leader on the streets outside Miraflores Palace on what was supposed to be his inauguration day. With Chavez out of sight in a Cuban hospital fighting a severe respiratory infection more than a month after cancer surgery, his swearing-in ceremony has been indefinitely postponed, despite opposition complaints.

“We came to show support, so he knows his nation is with him,” said Anny Marquez, a secretary and voluntary member of a civilian militia that Chavez has built in recent years. “We’re with him in the good times as well as the bad.”

The government invited leaders from across Latin America and the Caribbean to add political weight to the inauguration without an inauguree, while the domestic opposition demanded details about Chavez’s state and called the delay of the formal swearing-in a violation of the constitution.

Presidents attending from allied countries included President Jose Mujica of Uruguay, Evo Morales of Bolivia and Daniel Ortega of Nicaragua.

Vice President Nicolas Maduro, whom Chavez designated his chosen successor last month, hosted a televised meeting with visiting leaders to discuss the Chavez-launched Petrocaribe program, through which the OPEC nation provides fuel under preferential terms to allies. Maduro said heads of state, foreign ministers and other officials from 19 countries had come to Caracas.

Maduro said the leaders would go to the presidential palace in the afternoon for the “main event.” He said earlier that even though it wasn’t an official swearing-in, Thursday’s event still marks the start of a new term for the president following his re-election in October.

“A historic period of this second decade of the 21st century is starting, with our commander leading,” Maduro said.

But glaring above all in the at times surreal event was Chavez’s absence from the balcony of the presidential palace where he has so often spoken for hours to similar crowds, chiding his opponents and called for a socialist revolution.

As in past rallies before the president himself, Chavez’s face beamed from shirts, signs, banners and murals. Some danced to music blaring from speakers mounted on trucks. Nearly everyone wore the color of his Bolivarian Revolution movement as the swelling crowd grew into a sea of red and spilled from the main avenue onto side streets.

The crowd chanted: “We are all Chavez!”

It was the first time in Venezuela’s history that a president has missed his inauguration, said Elias Pino Iturrieta, a prominent historian. “Perhaps it’s the first chapter of what they call Chavismo without Chavez.”

The Supreme Court on Wednesday backed the plan to put off the inauguration indefinitely, saying the president could be sworn in before the court at a later date.

Chavez has been fighting an unspecified type of pelvic cancer since June 2011 and has undergone repeated surgeries, chemotherapy and radiation treatments. The government said in its last update on Monday that Chavez was in a “stable situation” while being treated for a severe respiratory infection. The government has hasn’t said how severe his “respiratory deficiency” is.

Hundreds of National Guard troops and police stood guard on street corners while hip-hop artists performed on stages set up along the avenue leading toward the presidential palace. Many in the crowd held up posters reading: “Now with Chavez more than ever.”

“We’re Chavez. Chavez is now an ideology,” said Elio Silva, a member of the radical Tupamaro grass-roots group who traveled five hours by bus for the event. He wore a black beret with a single star, a style once worn by Argentine revolutionary Ernesto “Che” Guevara.

Silva said he holds out hope that Chavez is recovering, and said he is sure that whatever happens in the weeks to come, “it will all be democratic.”

Vendors sold caps and shirts with images of Chavez. Some wore felt hearts in the colors of Venezuela’s flag pinned to their shirts, with pictures of Chavez pasted atop the hearts.

In a remark that echoed the sentiments of many in the crowd, teacher Marcelo Villegas said: “Unfortunately, Chavez can’t be with us today. But we the people represent Chavez. He is and always will be our leader.”